The pretentious read
The friction often arrives when a partner experiences sex as fundamentally physical and personal, and reads the larger-frame framing as either pretentious or performative. "It's just sex" lands, in this reach, the way "It's just dinner" would land for someone who actually cares about food.
What helps
"I want this to mean something to us too." "Let's slow down enough for it to actually land." What helps: a partner who can occasionally meet the deeper register without making it self-conscious. Even one in ten can change the texture of the whole relationship. The partner doesn't have to share the framing to honor it; they just have to recognize that this reach isn't performance, it's a real reach for a quality of presence the body has been asking for.